This application proposes to study the effect of malpractice liability reforms on health care practices, costs and outcomes. The research focuses on the practice of "defensive" medicine, which is defined as the delivery of services to the patient which are of little or no medical value, but may be instrumental in avoiding potential malpractice suits. The research investigates three specific questions: 1) the effect of different kings of malpractice reforms on the "malpractice pressures" facing health care providers and 2) the effect of tort reforms and malpractice pressure on medical treatment patterns for health problems more commonly involved in malpractice litigation and 30 the effect of malpractice-related differences in treatment patterns on health care costs and health outcomes.